The following descriptions and examples are not admitted to be prior art by virtue of their inclusion within this section.
Certain optoelectronic packages include components that are mounted at an angle (i.e., a mounting angle) relative to other components or mounting surfaces in the optoelectronic package. One such angled component is a photodetector. The term photodetector generally refers to any type of radiation detector that detects electromagnetic radiation. A photodetector may be used in a laser package (e.g., in an optical transmitter) to monitor light being emitted from a laser and coupled into an optical fiber. A photodetector may also be used in a photodetector package (e.g., in an optical receiver) to receive and detect light exiting an optical fiber.
In a laser package, for example, the photodetector is commonly provided in the same package as the laser to function as a check device to verify the proper operation of the laser. This photodetector is sometimes referred to as a “monitor photodetector” or “monitor photodiode,” due to its function in monitoring the output power of the laser. In such laser packages, a fiber may be mounted to receive the primary laser light output from a laser diode and a photodiode may be mounted to receive the small portion of light emitted from the back of the laser diode. This photodiode may be mounted at an intermediate angle between 0° and 90° relative to the emitted light because an angle of 0° may detect too little light and an angle of 90° may cause excessive back reflection. Likewise, a photodiode may be mounted at an angle within a photodetector package in a receiver so that the light output from the output end of the fiber is directed onto the active or light-receiving region of the surface of the photodiode.
One example of an optoelectronic package is a TO (transistor outline) can type package, which may be used to align and position the photodetector, laser, fiber, and/or related optical components. Other optical components may include collimation and coupling lenses, isolators, and the like to optically couple the laser or photodiode to the fiber. These components may be mounted in the TO can package (e.g., to the TO can post and/or header), and an optical fiber may be aligned with the components and coupled to the package (e.g., sometimes referred to as fiber pigtailing). As mentioned above, some of these components (e.g., the photodetector) may be mounted at a mounting angle (e.g., between 0° and 90° in the TO can package), other components may not be angled (i.e., a mounting angle of 0°) and yet other components may be mounted at a 90° angle.
The optical components may be electrically interconnected by wires and/or conductive traces. A wire may also connect an optical component to a substrate and/or an electrical contact that is connected to a conductive pin. A wire may be attached to an optical component, conductive trace, substrate and/or electrical contact using a wire bonding process. Wire bonding processes include thermocompression, ultrasonic and/or thermosonic processes. In the thermocompression process, bonding occurs at relatively high pressure and temperature (e.g., about 300° C. to about 500° C.). Ultrasonic and thermosonic processes use ultrasonic energy to form the bonds. In the thermosonic process, bonding occurs at a relatively moderate temperature (e.g., about 100° C. to about 240° C.).
To mount the components (e.g., laser diodes, photodiodes, lenses, and the like) in the proper locations with the desired mounting angles and to bond the wires, the optoelectronic package may be first secured in a fixture. A pick and place machine may then precisely position the components in the appropriate mounting location within the package for bonding to the mounting surface. Mounting components at an angle using these machines presents unique challenges because the pick and place machines generally position components straight into the package (i.e., not at an intermediate mounting angle).
Bonding the wires in the proper locations and to components that have been mounted at angles may also present unique challenges because wire bonding machines are generally configured to bond wires to surfaces that are generally horizontal with respect to the wire bonding machine. Further, for wire bonding processes that include ultrasonic energy, the surfaces to be bonded must be held firmly to ensure proper coupling of ultrasonic energy. Fixtures exist for wire bonding but are limited in that, in some cases, only one optical package may be accommodated at a time, the fixture may be positioned only at 0° or 90° relative to a horizontal plane and/or the fixture may not withstand and/or be capable of being heated.